This invention relates to a distributed data processing system of the type wherein a plurality of processors are connected to one another through a transmission line, and more particularly to a method and apparatus for synchronization management of timers of a plurality of processors for the same or each group.
A conventional timer synchronization management method is described, for example, in Japanese Patent Laid-Open No. 135,565/1984. According to this reference, a plurality of processors are connected to one another through a transmission line, a particular processor is defined as a "master" with the others being "slaves" for timer synchronization and the timer of each processor is synchronized by a synchronization instruction of the master processor.
However, such a conventional timer synchronization management method does not take into consideration back-up measures for possible extension and modification of the system and breakdown of the timer synchronization master system and hence involves the problems in extensibility, maintenance and reliability of the system.
In addition, it has been difficult in this prior art system to partially modify the time of processors forming the same group of the distributed data processing system for testing purpose.